The CDC said the 22 people infected are in seven states: Colorado, Indiana, Nebraska, New Mexico, Oklahoma, Texas and West Virginia.

Jensen Farms spokeswoman Amy Philpott said Thursday that one of the Colorado farm's Rocky Ford cantaloupes tested positive for the bacteria, but more tests are needed to determine if it's the same strain linked to the outbreak. The farm provides about 40 percent of the area's cantaloupes, Philpott said.

In cooperation with the voluntary recall, Safeway Inc. said it was recalling jumbo cantaloupes supplied by Jensen Farms and sold in Colorado; Nebraska; Aztec and Farmington, N.M.; South Dakota and Wyoming between Aug. 30 and Sept. 6. Cantaloupes currently in Safeway stores are not from the Rocky Ford region, the grocery chain said.

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It is first time the bacteria has been linked to cantaloupe in the U.S. The outbreak apparently originated in Rocky Ford, a fertile melon-growing area of Colorado that is a popular destination for tourists.

Tammie Palmer, of Colorado Springs, said Thursday her 71-year-old husband remains hospitalized after eating contaminated cantaloupe and she filed a lawsuit against Jensen Farms and Wal-Mart Stores Inc., where the family said the cantaloupe was purchased.

Palmer told The Associated Press that Charles Palmer got sick Aug. 31 and was rushed to the hospital, where doctors diagnosed it as Listeria monocytogenes, the same strain blamed for the outbreak.

"He wasn't able to talk to me for five days. When I talked to him, his eyes rolled into the back of his head. It's been a nightmare," she said.

Palmer said she was contacted by the Colorado health department, which wanted to know what groceries they bought, what they ate and where they stored the food. Philpott said she had not seen the lawsuit filed Thursday and had no comment.

Walmart spokesman Greg Rossiter said Palmer's illness was the first time the company has heard that somebody might have been sickened by cantaloupe bought at a Walmart.

"We take these concerns very seriously and we wish Mr. Palmer well," he said in a phone interview with The Associated Press.

Rossiter said the company removed cantaloupes on Monday and has been working with suppliers to find melons that come from safe areas.

Rossiter had not seen the lawsuit and declined to comment on specific allegations, which include selling a defective product.

Philpott said the company was informed that there was a positive test, "but we don't know if it was linked to the outbreak."

Philpott said she did not know the state or the store, or the agency that found it, and the recall was voluntary.

She said the company shipped more than 300,000 cases across the country during the period covered by the recall, but the company has recalled the entire harvest as a precaution.

The farm stopped harvesting on Monday when Colorado health officials issued an alert and notified retailers to remove the cantaloupes from shelves, Philpott said.

New Mexico has blamed three deaths on the outbreak, but epidemiologist Chad Smelser said Thursday that one death has been confirmed and the other two are pending results from the CDC.

The CDC said almost all of the victims interviewed remember eating cantaloupe and several remembered that they were from the Rocky Ford region.

The agency said about 800 cases of listeria are diagnosed in the United States each year and there are three or four outbreaks of it a year. Deli meats, hot dogs and cheese are the most frequent carriers, and outbreaks in produce are rare. Sprouts caused an outbreak in 2009, however, and celery caused an outbreak in 2010.

Cantaloupe is often a culprit in foodborne illness outbreaks, but not listeriosis. Earlier this year, state and federal authorities linked 12 salmonella illnesses, many of them in the West, to cantaloupes imported from Guatemala.

The cantaloupes were shipped between July 29 and Sept. 10 and distributed throughout Colorado, Wyoming, Nebraska, Utah, Kansas, Texas, Oklahoma, New Mexico, Arizona, Illinois, Minnesota, Missouri, Tennessee, North Carolina, New Jersey, New York and Pennsylvania.